High pressure water has long been used to clean blocked and silted drainage, sewer, and other conduits. Water is pumped through a flexible hose at high pressure and is expelled controllably at a downstream nozzle. Jets on the nozzle direct the discharging water angularly with respect to the hose in a trailing direction.
To effect a cleaning operation, the nozzle, which is normally at the leading end of the hose, is introduced to the sewer or other conduit to be cleaned. The water discharging from the jets propels the nozzle and hose forwardly through the conduit. At the same time, the pressurized water scours the walls of the conduit, if excessive or stubborn buildup is present in the conduit, a leading jet may be provided to propel liquid forwardly to break through any obstruction and define a path for the nozzle.
The above technique is employed using different nozzle and hose types, different flow rates and volumes and different pressures, as the particular job dictates. With this technique, it is possible to penetrate and effectively clean conduits up to 400 feet in length. This length is generally the maximum that is encountered for industrial, municipal, and household applications by reason of the regular access afforded through manholes.
While it may be possible to penetrate longer conduits with the above described technique, this technique may not be adequate where curves, elbows, and traps are encountered and/or when the conduit length significantly exceeds 400 feet. To enhance advancement of the nozzle, particularly through a long, circuitous conduit pathway, and break up obstructions, it is known to interrupt the nozzle flow to produce a pulsed fluid delivery through the nozzle by repetitive interruption of high pressure flow through the nozzle. The interruption causes a pulsating action in the nozzle and reduces overall friction between the hose and the conduit wall as the hose advances through a conduit over or around an obstruction because the pulsating action causes the hose to “jump” and thereby break contact between the hose surface and conduit and/or blockage.
Systems are currently known for producing a pulsed delivery of a fluid, but these systems have drawbacks which demonstrate the need for an improved fluid pump.
U.S. Pat. No. 5,580,225 (Salecker), herein incorporated by reference, discloses a pulsation causing check valve assembly for a plural piston pump system Salecker employs a check valve having a hole there through which provides open communication between the outlet manifold of the pump and the piston chamber, and a blocking and sealing structure associated with the check valve for blocking and sealing the opening. When the hole is not blocked or sealed, fluid can flow from the outlet manifold into the piston cylinder and fluid exits the pump in a pulsed or vibratory flow. However, this patent does not completely solve the above problems. In particular, this arrangement causes wear in the check valve. Furthermore, fluid flow from the check valve is not completely shut off.
U.S. Pat. No. 6,045,334 (Murphy), herein incorporated by reference, discloses a valve disabler for use in high pressure pipe cleaning operations. Unlike Salecker, which partially disables flow to the output manifold in a single valve, Murphy completely disables flow from the input manifold into a single cylinder. Murphy employs an adjusting stem to lock the valve poppet into position against the valve seat such that the valve poppet cannot be removed from the valve seat. This effectively thwarts the ingress of fluid into the cylinder associated with the valve disabler, which, in turn, renders the outlet valve virtually useless in its pumping capacity. However, this arrangement causes cavitations or starving of the associated cylinder which harms the pump.
There is a need for a pulsation causing valve for a plural piston pump which addresses the above problems.